Infectious Disease

Selleck EM, Gilmore MS. Oxygen as a Virulence Determinant in Polymicrobial Infections. MBio 2016;7(4)Abstract

Infections caused by multiple organisms, or polymicrobial infections, are likely more common than is broadly appreciated. Interaction among microbial communities (and with their host) can change the infection landscape by subverting immunity, providing nutrients and inhibiting competing microbes. Stacy et al. (A. Stacy, D. Fleming, R. J. Lamont, K. P. Rumbaugh, and M. Whiteley, mBio 7:e00782-16, 2016, described a novel mechanism that results in synergistic growth of oral microbes Aggregatibacter actinomycetemcomitans and Streptococcus gordonii The authors used whole-genome fitness profiling by transposon sequencing (Tn-seq) to identify genes differentially required for growth in vitro versus in a mono- or coinfection in a thigh abscess model. They found that coinfection with S. gordonii allowed A. actinomycetemcomitans to shift from an anaerobic to an aerobic mode of growth. This shift involved the production of a terminal electron acceptor H2O2 by S. gordonii and increased A. actinomycetemcomitans persistence-an interaction termed "cross-respiration."

Cho H, Shin YU, Siegel NH, Yu HG, Sobrin L, Patel A, Durand ML, Miller JW, Husain D. Endogenous Endophthalmitis in the American and Korean Population: An 8-year Retrospective Study. Ocul Immunol Inflamm 2016;:1-8.Abstract

PURPOSE: To study the clinical features of endogenous endophthalmitis (EE) in sample patient populations from the USA and South Korea over an 8-year period. METHODS: We reviewed data from 128 eyes of 60 American and 48 Korean patients diagnosed with EE and compared their clinical characteristics. RESULTS: Fungemia and liver abscess were the most common extraocular infection sources among American (26.7%) and Korean patients (33.3%), respectively. Klebsiella pneumoniae and Candida species were the most common pathogens of EE in the Korean and the American patients, respectively. Endophthalmitis caused by fungi had a better visual prognosis than that caused by bacteria (p = 0.001). Vitrectomy was beneficial for eyes with EE due to virulent bacteria presenting with worse than counting finger vision. CONCLUSIONS: The predisposing conditions and responsible organisms for EE vary in different regions of the world. The visual prognosis was strongly influenced by the underlying pathogen.

García-Solache M, Lebreton F, McLaughlin RE, Whiteaker JD, Gilmore MS, Rice LB. Homologous Recombination within Large Chromosomal Regions Facilitates Acquisition of β-Lactam and Vancomycin Resistance in Enterococcus faecium. Antimicrob Agents Chemother 2016;60(10):5777-86.Abstract

The transfer of DNA between Enterococcus faecium strains has been characterized both by the movement of well-defined genetic elements and by the large-scale transfer of genomic DNA fragments. In this work, we report on the whole-genome analysis of transconjugants resulting from mating events between the vancomycin-resistant E. faecium C68 strain and the vancomycin-susceptible D344RRF strain to discern the mechanism by which the transferred regions enter the recipient chromosome. Vancomycin-resistant transconjugants from five independent matings were analyzed by whole-genome sequencing. In all cases but one, the penicillin binding protein 5 (pbp5) gene and the Tn5382 vancomycin resistance transposon were transferred together and replaced the corresponding pbp5 region of D344RRF. In one instance, Tn5382 inserted independently downstream of the D344RRF pbp5 gene. Single nucleotide variant (SNV) analysis suggested that entry of donor DNA into the recipient chromosome occurred by recombination across regions of homology between donor and recipient chromosomes, rather than through insertion sequence-mediated transposition. The transfer of genomic DNA was also associated with the transfer of C68 plasmid pLRM23 and another putative plasmid. Our data are consistent with the initiation of transfer by cointegration of a transferable plasmid with the donor chromosome, with subsequent circularization of the plasmid-chromosome cointegrant in the donor prior to transfer. Entry into the recipient chromosome most commonly occurred across regions of homology between donor and recipient chromosomes.

Jain R, Sharma N, Basu S, Iyer G, Ueta M, Sotozono C, Kannabiran C, Rathi VM, Gupta N, Kinoshita S, Gomes JAP, Chodosh J, Sangwan VS. Stevens-Johnson syndrome: The role of an ophthalmologist. Surv Ophthalmol 2016;61(4):369-99.Abstract

Stevens-Johnson syndrome (SJS) is an acute blistering disease of the skin and mucous membranes. Acute SJS leads to the acute inflammation of the ocular surface and chronic conjunctivitis. If not properly treated, it causes chronic cicatricial conjunctivitis and cicatricial lid margin abnormalities. Persistent inflammation and ulceration of the ocular surface with cicatricial complications of the lids leads to chronic ocular sequelae, ocular surface damage, and corneal scarring. The destruction of the glands that secrete the tear film leads to a severe form of dry eye that makes the management of chronic SJS difficult. The option that is routinely used for corneal visual rehabilitation, keratoplasty, is best avoided in such cases. We describe the management strategies that are most effective during the acute and chronic stages of SJS. Although treatments for acute SJS involve immunosuppressive and immunomodulatory therapies, amniotic membrane transplantation is also useful. The options for visual rehabilitation in patients with chronic SJS are undergoing radical change. We describe the existing literature regarding the management of SJS and highlight recent advances in the management of this disorder.

Deiner MS, Lietman TM, McLeod SD, Chodosh J, Porco TC. Surveillance Tools Emerging From Search Engines and Social Media Data for Determining Eye Disease Patterns. JAMA Ophthalmol 2016;134(9):1024-30.Abstract

IMPORTANCE: Internet-based search engine and social media data may provide a novel complementary source for better understanding the epidemiologic factors of infectious eye diseases, which could better inform eye health care and disease prevention. OBJECTIVE: To assess whether data from internet-based social media and search engines are associated with objective clinic-based diagnoses of conjunctivitis. DESIGN, SETTING, AND PARTICIPANTS: Data from encounters of 4143 patients diagnosed with conjunctivitis from June 3, 2012, to April 26, 2014, at the University of California San Francisco (UCSF) Medical Center, were analyzed using Spearman rank correlation of each weekly observation to compare demographics and seasonality of nonallergic conjunctivitis with allergic conjunctivitis. Data for patient encounters with diagnoses for glaucoma and influenza were also obtained for the same period and compared with conjunctivitis. Temporal patterns of Twitter and Google web search data, geolocated to the United States and associated with these clinical diagnoses, were compared with the clinical encounters. The a priori hypothesis was that weekly internet-based searches and social media posts about conjunctivitis may reflect the true weekly clinical occurrence of conjunctivitis. MAIN OUTCOMES AND MEASURES: Weekly total clinical diagnoses at UCSF of nonallergic conjunctivitis, allergic conjunctivitis, glaucoma, and influenza were compared using Spearman rank correlation with equivalent weekly data on Tweets related to disease or disease-related keyword searches obtained from Google Trends. RESULTS: Seasonality of clinical diagnoses of nonallergic conjunctivitis among the 4143 patients (2364 females [57.1%] and 1776 males [42.9%]) with 5816 conjunctivitis encounters at UCSF correlated strongly with results of Google searches in the United States for the term pink eye (ρ, 0.68 [95% CI, 0.52 to 0.78]; P < .001) and correlated moderately with Twitter results about pink eye (ρ, 0.38 [95% CI, 0.16 to 0.56]; P < .001) and with clinical diagnosis of influenza (ρ, 0.33 [95% CI, 0.12 to 0.49]; P < .001), but did not significantly correlate with seasonality of clinical diagnoses of allergic conjunctivitis diagnosis at UCSF (ρ, 0.21 [95% CI, -0.02 to 0.42]; P = .06) or with results of Google searches in the United States for the term eye allergy (ρ, 0.13 [95% CI, -0.06 to 0.32]; P = .19). Seasonality of clinical diagnoses of allergic conjunctivitis at UCSF correlated strongly with results of Google searches in the United States for the term eye allergy (ρ, 0.44 [95% CI, 0.24 to 0.60]; P < .001) and eye drops (ρ, 0.47 [95% CI, 0.27 to 0.62]; P < .001). CONCLUSIONS AND RELEVANCE: Internet-based search engine and social media data may reflect the occurrence of clinically diagnosed conjunctivitis, suggesting that these data sources can be leveraged to better understand the epidemiologic factors of conjunctivitis.

Ismail AM, Lee JS, Dyer DW, Seto D, Rajaiya J, Chodosh J. Selection Pressure in the Human Adenovirus Fiber Knob Drives Cell Specificity in Epidemic Keratoconjunctivitis. J Virol 2016;90(21):9598-9607.Abstract

Human adenoviruses (HAdVs) contain seven species (HAdV-A to -G), each associated with specific disease conditions. Among these, HAdV-D includes those viruses associated with epidemic keratoconjunctivitis (EKC), a severe ocular surface infection. The reasons for corneal tropism for some but not all HAdV-Ds are not known. The fiber protein is a major capsid protein; its C-terminal "knob" mediates binding with host cell receptors to facilitate subsequent viral entry. In a comprehensive phylogenetic analysis of HAdV-D capsid genes, fiber knob gene sequences of HAdV-D types associated with EKC formed a unique clade. By proteotyping analysis, EKC virus-associated fiber knobs were uniquely shared. Comparative structural modeling showed no distinct variations in fiber knobs of EKC types but did show variation among HAdV-Ds in a region overlapping with the known CD46 binding site in HAdV-B. We also found signature amino acid positions that distinguish EKC from non-EKC types, and by in vitro studies we showed that corneal epithelial cell tropism can be predicted by the presence of a lysine or alanine at residue 240. This same amino acid residue in EKC viruses shows evidence for positive selection, suggesting that evolutionary pressure enhances fitness in corneal infection, and may be a molecular determinant in EKC pathogenesis. IMPORTANCE: Viruses adapt various survival strategies to gain entry into target host cells. Human adenovirus (HAdV) types are associated with distinct disease conditions, yet evidence for connections between genotype and cellular tropism is generally lacking. Here, we provide a structural and evolutionary basis for the association between specific genotypes within HAdV species D and epidemic keratoconjunctivitis, a severe ocular surface infection. We find that HAdV-D fiber genes of major EKC pathogens, specifically the fiber knob gene region, share a distinct phylogenetic clade. Deeper analysis of the fiber gene revealed that evolutionary pressure at crucial amino acid sites has a significant impact on its structural conformation, which is likely important in host cell binding and entry. Specific amino acids in hot spot residues provide a link to ocular cell tropism and possibly to corneal pathogenesis.

Cruzat A, Hamrah P, Cavalcanti BM, Zheng L, Colby K, Pavan-Langston D. Corneal Reinnervation and Sensation Recovery in Patients With Herpes Zoster Ophthalmicus: An In Vivo and Ex Vivo Study of Corneal Nerves. Cornea 2016;35(5):619-25.Abstract

PURPOSE: To study corneal reinnervation and sensation recovery in Herpes zoster ophthalmicus (HZO). METHODS: Two patients with HZO were studied over time with serial corneal esthesiometry and laser in vivo confocal microscopy (IVCM). A Boston keratoprosthesis type 1 was implanted, and the explanted corneal tissues were examined by immunofluorescence histochemistry for βIII-tubulin to stain for corneal nerves. RESULTS: The initial central corneal IVCM performed in each patient showed a complete lack of the subbasal nerve plexus, which was in accordance with severe loss of sensation (0 of 6 cm) measured by esthesiometry. When IVCM was repeated 2 years later before undergoing surgery, case 1 showed a persistent lack of central subbasal nerves and sensation (0 of 6). In contrast, case 2 showed regeneration of the central subbasal nerves (4786 μm/mm) with partial recovery of corneal sensation (2.5 of 6 cm). Immunostaining of the explanted corneal button in case 1 showed no corneal nerves, whereas case 2 showed central and peripheral corneal nerves. Eight months after surgery, IVCM was again repeated in the donor tissue around the Boston keratoprosthesis in both patients to study innervation of the corneal transplant. Case 1 showed no nerves, whereas case 2 showed new nerves growing from the periphery into the corneal graft. CONCLUSIONS: We demonstrate that regaining corneal innervation and corneal function are possible in patients with HZO as shown by corneal sensation, IVCM, and ex vivo immunostaining, indicating zoster neural damage is not always permanent and it may recover over an extended period of time.

Chen Y, Liu F, Wang C, Zhao M, Deng L, Zhong J, Zhang Y, Ye J, Jing S, Cheng Z, Guan Y, Ma Y, Sun Y, Zhu B, Zhang Q. Molecular Identification and Epidemiological Features of Human Adenoviruses Associated with Acute Respiratory Infections in Hospitalized Children in Southern China, 2012-2013. PLoS One 2016;11(5):e0155412.Abstract

BACKGROUND: Acute respiratory infections (ARI) are the major worldwide health problem associated with high morbidity and mortality rates. Human adenovirus (HAdV) is one of the most common pathogens associated with viral ARI, and thus calls for specific diagnosis and better understanding of the epidemiology and clinical characteristics. METHODS: Total 4,130 children with ARI requiring hospitalization from 2012 to 2013 were retrospectively studied. Throat swab specimens were collected from each patient. Fluorescence Quantitative PCR was performed to detect adenovirus as well as other common ARI-related pathogens. The seven HAdV hypervariable regions (HVRs) of the hexon gene from fifty-seven HAdVs-positive samples collected in the seasonal peaks were sequenced. Phylogenetic analysis of HVRs was also conducted to confirm the molecular types and genetic variation. In addition, epidemiological features and co-infection with other human respiratory pathogens were investigated and analyzed. RESULTS: Of 4,130 hospitalized pediatric patients tested, the positive rates of respiratory syncytial virus (RSV), Mycoplasma pneumoniae (MP), and HAdV were 13.7%, 13.2%, and 12.0%, respectively. The HAdV positive patients accounted for 7.9%, 17.2%, 17.5% and 10.7% in age groups <1, 1-3, 3-6 and 6-14 years, respectively. Eighty-four HAdV positive children were co-infected with other respiratory pathogens (84/495, 17.0%). The most common co-infection pathogens with HAdV were MP (57.1%) and Human Bocavirus (HBoV) (16.7%). The majority of HAdV infected patients were totally recovered (96.9%, 480/495); However, four (0.8%) patients, who were previously healthy and at the age of 2 years or younger died of pneumonia. Seasonal peaks of HAdV infection occurred in the summer season of 2012 and 2013; the predominant HAdV type was HAdV-3 (70%), followed by HAdV-7 (28%). These epidemiological features were different from those in Northern China. The HAdV-55 was identified and reported for the first time in Guangzhou metropolitan area. Phylogenetic analysis indicated that all the HVR sequences of the hexon gene of HAdV-3 and -7 strains have high similarity within their individual types, and these strains were also similar to those circulating in China currently, indicating the conservation of hexon genes of both HAdV-3 and HAdV-7. CONCLUSIONS: Knowledge of the epidemiological features and molecular types of HAdV, a major pathogen of pediatric ARI, as well as other co-infected respiratory pathogens circulating in Guangzhou, southern China, is vital to predict and prevent future disease outbreaks in children. This study will certainly facilitate HAdV vaccine development and treatment of HAdV infections in children.

Gaca AO, Gilmore MS. A lysin to kill. Elife 2016;5Abstract

An enzyme produced by a bacteriophage can enter human cells and kill intracellular Streptococcus pyogenes.

Hong J, Zhong T, Li H, Xu J, Ye X, Mu Z, Lu Y, Mashaghi A, Zhou Y, Tan M, Li Q, Sun X, Liu Z, Xu J. Ambient air pollution, weather changes, and outpatient visits for allergic conjunctivitis: A retrospective registry study. Sci Rep 2016;6:23858.Abstract

Allergic conjunctivitis is a common problem that significantly impairs patients' quality of life. Whether air pollution serves as a risk factor for the development of allergic conjunctivitis remains elusive. In this paper, we assess the relationship between air pollutants and weather conditions with outpatient visits for allergic conjunctivitis. By using a time-series analysis based on the largest dataset ever assembled to date, we found that the number of outpatient visits for allergic conjunctivitis was significantly correlated with the levels of NO2, O3, and temperature, while its association with humidity was statistically marginal. No associations between PM10, PM2.5, SO2, or wind velocity and outpatient visits were seen. Subgroup analyses showed that sex seemed to modify the effects of humidity on outpatient visits for allergic conjunctivitis, but not for NO2, O3, or temperature. People younger than 40 were found to be susceptible to changes of all four parameters, while those older than 40 were only consistently affected by NO2 levels. Our findings revealed that higher levels of ambient NO2, O3, and temperature increase the chances of outpatient visits for allergic conjunctivitis. Ambient air pollution and weather changes may contribute to the worsening of allergic conjunctivitis.

Odorcic S, Haas W, Gilmore MS, Dohlman CH. Fungal Infections After Boston Type 1 Keratoprosthesis Implantation: Literature Review and In Vitro Antifungal Activity of Hypochlorous Acid. Cornea 2015;34(12):1599-605.Abstract

PURPOSE: To review the current literature describing cases of fungal keratitis and endophthalmitis after Boston keratoprosthesis (KPro) implantation and to characterize the antifungal activity of 0.01% hypochlorous acid against medically relevant fungi. METHODS: A literature review of fungal keratitis or endophthalmitis in KPro patients from January 2001 to April 2015, and an in vitro time kill assay characterizing the fungicidal activity of 0.01% hypochlorous acid against fungi causing ocular infections. RESULTS: Fifteen publications, predominantly retrospective case series, were identified. Infection rates after KPro implantation ranged from 0.009 to 0.02 fungal infections per patient-year of follow-up. The largest single-surgeon series reported an incidence of 2.4% for fungal endophthalmitis during a 10-year period. Causative organisms included both yeasts and molds. Outcomes were favorable if infections were caught early and treated appropriately; less favorable outcomes were reported in developing countries where fungal species are endemic and resources are limited. 0.01% hypochlorous acid is rapidly fungicidal, reducing the number of viable yeast cells or mold conidia by at least 99.99% within 60 seconds. The antifungal activity extended to all molds (Acremonium kiliense, Aspergillus flavus, Aspergillus fumigatus, Fusarium solani, and Mucor indicus) and yeast species (Candida albicans and Candida parapsilosis) tested. CONCLUSIONS: Fungal infections remain a lifelong concern in patients after KPro implantation. There is a growing need for a standard antifungal prophylaxis regimen, especially in the developing world. The rapid broad-spectrum in vitro fungicidal activity of 0.01% hypochlorous acid against all fungi tested makes it an attractive candidate as an antifungal prophylaxis in KPro patients.

Chi M, Kim JH, Basham R, Yoon MK, Vagefi R, Kersten RC. Temporal Artery Calciphylaxis Presenting as Temporal Arteritis in a Case of Rhinoorbitocerebral Mucormycosis. Ophthal Plast Reconstr Surg 2015;31(5):e132-5.Abstract

Mucormycosis is a rare often fatal opportunistic fungal infection. It is typically described in patients with diabetes in ketoacidotic status and is rare in renal transplant recipients. Calciphylaxis is a rare and highly morbid disease of vascular calcification affecting patients with end-stage renal disease (ESRD). The first case of a renal transplant recipient who was inflicted with both rhinoorbitocerebral mucormycosis and calciphylaxis is reported. A 45-year-old man presented with 2-day history of left upper blepharoptosis, periorbital pain, left-sided headache, binocular diplopia, and left V2 numbness. He had undergone renal transplant for ESRD 7 months earlier with resultant immunosuppressive therapy. MRI and nasal biopsy confirmed rhinoorbitocerebral mucormycosis. Immunosuppressive therapy was stopped and antifungal therapy begun. He had orbital exenteration for progressive rhinoorbitocerebral mucormycosis. Two months later, the patient reported new-onset intermittent bitemporal headache and bilateral swollen, tender temporal arteries. Temporal artery biopsy revealed features consistent with calciphylaxis. Clinical presentation, treatment course, and follow up are discussed.